Solar Panels Explained

By Dzhingarov

Solar panels provide a clean and renewable source of electricity.

Solar panels consist of multiple silicon cells that absorb light during the day.

Photons striking cells cause electrons to be knocked free from their atoms, creating an electrical current.

Current flows through wires and is collected and combined by other solar cells in a panel.

The Cells

Solar panels consist of photovoltaic cells that capture sunlight and convert it to energy. These individual cells are connected in series and parallel, creating a panel which can be used for powering electrical devices, heating homes, or cooling buildings.

Solar cells are generally made of silicon, which absorbs and transforms light emitted by the sun. They’re designed to produce high-quality electricity that can be used both residentially and commercially.

Different solar cell types exist, such as monocrystalline and polycrystalline cells, as well as thin film ones. Some of these cell types boast higher efficiency levels than others, but each has its own advantages and drawbacks.

Monocrystalline silicon solar cells are the most commonly used type of solar cell. While monocrystalline cells tend to be the most efficient, producing higher levels of electricity per square foot at lower costs, their production costs are higher than those for polycrystalline cells and they don’t perform as well in high temperatures as polycrystalline does.

Another type of solar cell is polycrystalline, which consists of multiple crystals of silicon. While these cells have lower efficiency levels than monocrystalline models, they’re cheaper and simpler to manufacture.

Thin-film solar cells are a relatively new type of solar cell that has the potential to be highly efficient. They consist of thin films of semiconductor material layered, which requires less material and has lower fabrication costs.

These layers can absorb a wide range of wavelengths from the sun’s light, making them more efficient than single-junction cells with only one semiconductor layer.

Researchers are striving to maximize the efficiency of solar cells by layering different kinds of semiconductors together in multijunction cells. These devices can achieve record efficiency levels as they capture more light rays than single-junction cells do.

When a light-emitting diode is configured correctly, it creates a voltage difference between its n-type and p-type layers of semiconductor. This causes electrons in the n-type layer to move into holes in the p-type layer, emitting energy in the form of photons.

The Wires

Solar panels require wires to function, connecting them together and then to a charge controller and battery bank for optimal power generation.

When connecting solar panels together, there are various wire types and options. Your choice of wire depends on a few factors like the size and wattage of your panel, where it will be installed, and whether or not they will be run in series or parallel.

A series connection is created when the positive terminal on one solar panel is connected to the negative terminal on adjacent panels in a line (like a battery). Not only does this increase voltage in the circuit, but it also ensures consistent current at maximum power from one panel to another.

However, a series connection has the additional risk of arcing from one wire to the next, which could result in fires or other issues.

In such cases, it’s preferable to use wiring designed specifically for solar installations. There are a few wires suitable for this purpose such as USE-2 wire and PV wire.

PV Wire is a commonly used solar wire for interconnection wiring applications in colder climates. With thicker insulation and stranded wire construction for resilience and flexibility, this type of wire must pass both flame test and physical testing according to UL standards.

USE-2 wire is a widely-used solar cable with the same construction as PV wire. It can be used in both grounded and ungrounded arrays, though its improved heat resistance makes it better suited for ungrounded systems.

THHN wire is also frequently employed in solar installation, and it features a similar construction to USE-2 wire. It has an extra thick insulating layer on the conductor but that insulation isn’t necessary for solar panel setups since they draw less current.

Solar wires come in various gauges, and it’s essential to select the thickest UL-rated PV-specific wire you can afford for your project. Doing this will save money on replacements should additional panels need adding down the line.

The Glass

Solar panels must include glass as one of the essential elements. This glass shields photovoltaic cells from damage and acts as a mirror to focus light onto specific areas.

Furthermore, it provides structural strength to photovoltaic cell components and can withstand extreme weather conditions. Tempered soda-lime glass has been chemically treated to be stronger and less vulnerable to breakage than regular window or drinking glasses.

Some manufacturers employ sol-gel nanomaterials and precision coating technology to coat a layer of nanomaterial film on solar glass surfaces, improving its performance as an insulator and increasing efficiency. This coating allows more energy to be converted into renewable electricity by reflecting sun rays and capturing more sunlight than standard commercial glass which transmits 83.7% of solar energy while absorbing 16.3%.

Another advantage of glass is its self-cleaning properties, which reduce maintenance expenses and keep your solar panels in excellent condition. The sleek surfaces make it effortless to wipe away dirt or dust that accumulates over time.

Additionally, air gaps help prevent water stains and rainwater from getting between the air gaps, which could reduce your solar panels’ efficiency. On plastic-covered panels this could mean an overall drop in energy output of up to 10%.

Glass also acts as a protective layer for your solar panels, shielding them from rocks or branches falling from trees that could damage their inner components. It can also be used to encase the solar cells, improving efficiency and increasing its lifespan.

It is also lightweight, making it simple to transport and install. For instance, a 250W c-Si solar panel laminated on 3.2mm thick glass weighs 20kg while a double-glass solar module has two layers of tempered glass on either side.

The Backsheet

A solar panel’s backsheet is the final layer that safeguards and enhances its functionality. It shields from harsh environmental elements like water, dust, debris, insects and more that could disrupt system functioning. Furthermore, electrical isolation between cell internal circuitry from external influences helps safeguard cells as well as safeguard electrical connections throughout a house or business.

The backsheet of a panel is composed of either polymers or combinations designed to withstand extreme temperatures and weather conditions over its lifetime. These materials should also be resistant to thermal shrinkage while maintaining structure and form, as well as being scratch-resistant – particularly during installation and upkeep.

In addition to these properties, a PV backsheet must possess good adhesion and mechanical strength. This is essential for the module’s longevity and performance. Furthermore, weather-resistant properties ensure that cells and their electrical system remain shielded from rain, snow, sleet, ice, and other external elements.

Some PV manufacturers utilize inexpensive materials for their backsheets. Common options include low-stabilized PET or thin layers of fluoropolymers such as PVF (Tedlar) or PVDF.

Even though these backsheets offer better electrical insulation than PET, they still may be vulnerable to moisture and sunlight damage. To combat this issue, many companies incorporate high stability PET or PVDF/PVF into the core layer of their backsheets for extra durability.

Though more cost-effective than stabilizing the PET core, this approach could limit the lifespan of a PV panel. A recent study revealed that PA-based backsheets are susceptible to delamination in the field at an alarming 95% rate after only six years of operation.

These backsheet failures can result in power degradation, serious safety hazards and brand reputation losses. Furthermore, they have the potential to negatively affect an inverter’s performance and prevent it from producing energy.

Furthermore, poorly performing backsheet materials can drastically shorten a solar plant’s lifespan and cause significant increases in energy bills, loss of production and other negative consequences. Fortunately, solar plants are fully digitalised down to the module record level which helps detect problems like backsheet failure before they happen and mitigate their consequences.